Steering Wheel with Stationary Hub Mounted Portion

ABSTRACT

A steering wheel having a stationary portion supporting a DAB or similar module, comprises an armature ( 1 ) having a hub ( 2 , H) directly mounted to a vehicle steering shaft and provided with an opening ( 3 ) through which a coiled element ( 5 ) passes. A non-rotating housing ( 41 ) is assembled with the hub ( 2 ) and the coiled element ( 5 ) connects the non-rotating housing ( 41 ) to a fixed part ( 61 ) of the vehicle and carries one or more electric wires to the DAB. The coiled element ( 5 ) is screwing or unscrewing itself to or from the hub ( 2 , H) via the opening ( 3 ) when the steering wheel is rotated. A gear assembly is provided for supporting the stationary portion ( 41 ) when the steering wheel is rotated.

The present invention relates to a steering wheel having a stationaryhub mounted portion, in particular to a steering wheel having a staticdriver airbag module.

BACKGROUND OF THE INVENTION

A typical driver airbag module (DAB) is mounted on a vehicle steeringwheel usually fixed to a hub, which in turn is coupled to a steeringshaft. Consequently a DAB rotates in unison with the steering wheel.Since the deployment of the airbag may occur at different rotationangles of the steering wheel with respect to the vehicle driver, thesame airbag has to be circular or symmetrical shaped to provide alwaysthe same shape of protection surface to the driver.

In some motor vehicles, for instance in sport cars, the maximum diameterof the airbag is limited by the high inclination of the windscreen andthe front door jambs. Recently, assemblies have been provided that allowthe driver airbag module to remain in a stationary position with respectto the vehicle during rotation of the steering wheel. This type ofmodule is known as a static driver airbag module. Advantageously, staticDABs may provide airbags having shapes other than circular, since thereis no rotation of the same with respect to the driver. Stationarymodules allow for localized increases of the airbag volume. Thus airbagsmay be designed to fit the internal volume of a particular vehicle whendeployed, in such a way to better protect the driver regardless of theangular position of the steering wheel.

Different solutions have been provided for stationary mounting a DAB ona steering wheel.

US 2003/0067147 A1 discloses a static driver airbag assembly thatcomprises a rotatable steering wheel encompassing an accessible spaceand coupled to the respective shaft by a planetary gear system. Theplanetary gear system transfers torque applied to the steering wheelring portion directly to the steering shaft. An airbag module ispositioned within the accessible space encompassed by the steering wheeland remains in a stationary position during rotation of the steeringwheel.

DE 2131902 discloses a steering wheel provided with a non rotating DAB.Rotation of the steering wheel is transmitted to the steering shafteither directly, by matching the internal teeth of the steering hub withthe external teeth of the shaft, or indirectly by way of planetary gearsinterposed between the hub teeth and the shaft teeth. In both cases aspace is left between the shaft and the steering hub for housing of boththe electric wires and the stationary support elements to which the DABmodule is fixed. This is achieved by providing the hub with a greaterdiameter than the shaft and using the gap between them for the passageof the wires and the stationary support elements.

Solutions provided with planetary gears (as the solution shown in FIG. 2of DE 2131902) have several drawbacks. First, the steering wheel is notdirectly mounted on the steering shaft: thus, there is a discontinuityin the structure. Because of the increasing of the mechanical clearancewhich occurs as the above gears get worn with usage, rotation of thesteering wheel does not match with the rotation of the steering shaft.Moreover, when planetary gears are provided for connecting the steeringhub to the steering shaft, it is necessary that the assembly gears haveexact dimensions to avoid damping of the force transmitted by the driverto the steering shaft or the occurring of an offset between the rotationangle of the steering wheel ring portion and the rotation of thesteering shaft. If one of the static DAB components has dimensionsdifferent from what is specified, a non-uniform rotation of the steeringwheel ring portion may occur, for example due to the imperfect matchingbetween the gears.

There usually is another drawback: rotation of the steering shaft is inthe opposite direction with respect to the rotation imparted by thedriver to the steering wheel ring portion. The steering box of thevehicle has to be designed to overcome such drawback so as to reversethe direction of rotation imparted by the steering shaft to the vehiclewheels. This leads to an increase in the vehicle production costs.

More generally, prior art assemblies provided with gears for couplingthe steering hub to the steering shaft are complicated and require highaccuracy in the manufacture of the gears, with evident increasing inproduction time and costs.

DE 3413009 A1 discloses a steering wheel provided with a stationary DABmodule wherein the steering wheel hub is directly coupled to thesteering shaft, that is in a traditional way. Two gears are provided formaintaining the DAB module stationary: a first gear matching the DABmodule and a second gear matching the steering shaft. The first and thesecond gear are coupled to the same driving shaft which is rotatablylodged within a seat of the steering hub. When the driver rotates thesteering wheel ring portion, the second gear is rotated about its ownaxis by the steering shaft and is also rotated about the steering wheelaxis by the steering wheel hub pushing the driving shaft. The samemovement is transmitted by the driving shaft to the first gear. The gearratio between the first gear and the DAB module and between the secondgear and the steering shaft is chosen such that the DAB module rotatesin the opposite direction with respect to the steering wheel ringportion, thereby remaining stationary.

Such solution requires two expensive “clockspring” connectors to be usedfor cabling the DAB module. A first connector is arranged on thesteering shaft side of the hub and a second connector is arranged on thedriver side of the hub, wired to the first one through the same hub.Another drawback of the solution according to DE 3413009 A1 is that thecoupling of the driving shaft with the respective seat provided in thesteering hub is critical. Inaccuracy in the machining of the seat mayeasily lead to misalignment of the first and second gears, therebyinducing movements of the DAB module when the steering wheel ringportion is rotated.

U.S. Pat. No. 4,541,301 discloses a steering wheel assembly wherein theDAB module is supported stationary by a coiled element which screws orunscrews itself through a hub opening when the steering wheel is rotatedclockwise or counterclockwise. The coiled element has a first endcoupled to a stationary portion of the vehicle, a second end fixed tothe module and wounds around the steering shaft. The main drawback ofsuch solution is that the coiled element does not sufficiently resisttorsion to avoid the DAB module from incurring in small movements. Inother words, the coiled element does not provide the necessarymechanical strength to stationary support the DAB module in all theoperating conditions.

US 2003/0164060 A1 discloses a steering wheel for a vehicle providedwith a second shaft other than the steering shaft. The second shaft issupported via bearings by a stationary hub, which includes a DABhousing, such that it is rotatable about its own axis and is coupled tothe steering shaft by an arm or an electronic actuator. The actuatorincludes a position sensor for detecting an angular displacement of thesecond shaft from a selected origin and producing a signal indicative ofthe angular displacement. Such a signal is transmitted to a road wheelactuator so that the position of the road wheels properly correspondswith the position of the steering wheel.

Generally, solutions based on a plurality of shafts are complicated andexpensive. Duplication of the steering shaft facilitates passing theairbag module wiring harness easily inside the steering wheel column,but requires accurate design and assembly, expensive mechanicalcomponents and eventually electronic devices. Moreover, traditionalassemblies provided with a plurality of gears or shafts are normallycumbersome. Consequently, vehicle steering columns, i.e. the variouscomponents of the vehicle around and comprising the steering shaft, haveto be re-designed accordingly to accommodate such assemblies.

FR 2833916 discloses a steering wheel wherein the DAB module is keptquasi-stationary by way of an electric motor which is operated to rotatethe DAB module in the opposite direction with respect to the steeringwheel ring portion but for an initial angle. Such solution iscumbersome, complicated, expensive and difficult to assemble and to set.Moreover an electronic control unit is needed to sense the rotation ofthe ring portion of the steering wheel and operate the motorconsequently.

Therefore, there is the necessity of providing a reliable and compactdriver airbag module assembly that does not rotate with the steeringwheel and that can be fitted on existing steering columns without havingto re-design the same.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a steering wheelhaving a stationary central portion which overcomes the drawbacks ofknown solutions, being at the same time economical, reliable and simpleto manufacture and assemble.

It is a further object of the present invention to provide a steeringwheel having a stationary central portion which overcomes the drawbacksof prior art solutions related to the mechanical coupling between thesteering wheel and the steering shaft and at the same time overcomes thedrawbacks of prior art solutions related to the electrical connectionsof the DAB module.

It is a further object of the present invention to provide a steeringwheel having a stationary central portion that can be directly mountedon common steering columns in a traditional way, with no need forre-designing of the same columns.

It is a further object of the present invention to provide a steeringwheel having a stationary driver airbag module which is adaptable tovarious needs in terms of dimensions, styling and cost requirements.

These and other objects are achieved by the steering wheel according toclaim 1 of the present invention.

In a preferred embodiment of the invention, a coiled element supports anon-rotating housing via an opening through a steering wheel hub and thesame hub can be directly fixed to a steering shaft in a traditional way,for instance by coupling the shaft to the centre of the hub. Thus thesteering wheel according to the present invention does not need thevehicle steering column to be re-designed.

The coiled element preferably is a cylindrical helical element arrangedcoaxially with the steering wheel shaft, around the same, and is housedin two substantially symmetrical housings: a first non-rotating housingon the driver side of the hub and a second, stationary, housing on theopposite side of the hub, fixed to a fixed portion of the vehicle. Thecoiled element is fixed to both non-rotating and second, stationary,housings.

Thus, non-rotating housing, located on the hub facing the driver, isconnected to a stationary part of the vehicle by the coiled elementpassing through the opening or aperture provided in the hub. Rotation ofthe coiled element around the axis of rotation of the steering wheel issubstantially prevented. Consequently when the steering wheel isrotated, the hub rotates with respect to the coiled element and theopening runs on the coiled element, following its coils.

When the steering wheel is rotated and the hub aperture runs on thecoiled element (i.e. the coiled element spirals through the hubopening), an increasing or decreasing length of the coiled element (i.e.a greater or smaller number of coils) is located on the hub side facingthe driver, depending on the rotation being clockwise orcounterclockwise.

The coiled element may be rigid or, preferably, deformable to extendalong its longitudinal axis. Consequently the pitch between the coils ofthe coiled element, i.e. the distance between corresponding portions ofadjacent coils, may be constant or may change for the coils which aredisplaced axially by external forces.

If the coiled element is rigid the pitch between the coils is constantand sufficient to accommodate the hub between the two adjacent coils andmeans are provided for allowing axial movements of the same coiledelement when the hub is moving on the coils. Such means allow the coiledelement to move axially to screw and unscrew into and away from the hubwhich is itself axially fixed. For instance the ends of the coiledelement may slide within axial slots provided in the non-rotatinghousing and in the fixed part of the vehicle and bearings may beprovided to facilitate its sliding. Such means may be complicated todesign and manufacture.

Preferably the coiled element is resistant to torsion and axiallydeformable, i.e. elastically extensible and compressible along its axis;the pitch between two adjacent coils will thus adapt to accommodate thehub, i.e. when the hub is interposed between two adjacent coils, thesame coils are axially displaced by the hub from an initial, close,almost adjacent, position to an extended position, and when the hubproceeds along the coiled element the coils return to their initialposition. If the coiled element is elastically extensible, at least oneof its ends is axially fixed and the single coils may be axiallycompressed or extended to allow screwing and unscrewing into/from thehub which is itself fixed in the axial direction defined by the steeringshaft.

When the steering wheel is in its neutral position, corresponding to thevehicle directed straight forward, the same number of coils of thecoiled element may be located on opposite sides of the hub, for instancethree coils on the driver side of the hub and three coils on thesteering column side.

In a first embodiment of the invention, the coiled element is extensibleand provides a first end coupled to the non-rotating housing located onthe driver side of the hub. Rotation of the coiled element is preventedby coupling it to the fixed part of the vehicle, through the abovementioned second, stationary, housing. Thus also the rotation of thenon-rotating housing is prevented. When the hub rotates, thenon-rotating housing will slide on the hub; coupling between the hub andthe non-rotating housing will slidingly support the non-rotating housing(supporting the DAB) and axial movements are avoided, i.e. the hub willretain and support the non-rotating housing in the axial direction.

According to the invention, the non-rotating housing contains at least aportion of the coiled element. The housing is intended to accommodatethe coils of the coiled element that extend from the opening in the hubto the non-rotating housing, i.e. the coils that are “spiralled”, or“screwed”, through the hub into the driver side of the hub, possiblywithin the same housing, when the steering wheel is rotated.

The non-rotating housing can thus support one or more of a plurality ofdifferent devices such as electronic devices, an airbag module, etc.

In this first embodiment, a second end of the coiled element, oppositeto the first end with respect to the hub, is coupled to a fixed part ofthe vehicle, preferably by way of a second housing intended to containat least a portion of the coiled element. The second housingaccommodates the coils of the coiled element that extend from theopening of the hub to the fixed part of the vehicle, i.e. the coils thatare “unscrewed” from the driver side of the hub when the steering wheelis rotated. The coupling between the second housing and the hub is suchas to allow the rotation of the hub on the housing, for instance bysliding on the same, while axial movements of the housing is prevented.

If the coiled element is extensible and compressible, its total lengthis limited by the dimensions of the non-rotating housing and the secondhousing, i.e. the ends are fixed while the pitch between some coils willchange when the hub is located between such coils. The coiled elementpreferably is at least partially compressible along its longitudinalaxis, i.e. the coils may be separated in their initial position and mayabut one another when the coiled element is compressed.

The coiled element is designed to house means of carrying power and/orsignals through the hub. Wires or other conductors of power and signalsfor the devices mounted on the non-rotating housing are conveyed by thecoiled element from the steering wheel column to such devices. To thisend, the coiled element is provided with e.g. a continuous slot runningalong its coils to accommodate and protect from wear wires, harnesses orsupplies. Advantageously, the coiled element is thus used as a conveyorfor the electrical wires or harnesses instead of expensive standardclock-spring connectors.

According to a second embodiment of the steering wheel according to thepresent invention, in addition or alternatively to the coil, thenon-rotating housing is kept in position by a gear assembly, whichovercomes possible problems of insufficient strength of the coiledelement against torsion. The coiled element may be fixed to both thestationary part of the vehicle and to the non-rotating housing locatedon the hub facing the driver so as to cooperate with the gear assemblyfor supporting the non-rotating housing.

The non-rotating housing located on the hub and the second housing onthe fixed part of the vehicle are toothed and the gear assembly engagesboth them and the hub to compensate for rotation of the steering wheel.In particular, the gear assembly comprises a first gear, engaging thenon-rotating housing, and a second gear, engaging the second housing onthe fixed part of the vehicle. The first and second gears are coaxiallymounted on a same driving shaft which is rotatable in a seat of thesteering wheel hub (or in a hub housing). When the driver rotates thering portion of the steering wheel, the driving shaft is also rotatedwith the hub about the axis of the steering shaft. The first and secondgears, matching the respective stationary toothed portions, rotate abouttheir common axis. As a consequence, as the steering wheel is rotated,the non-rotating housing “rotates” in the opposite direction relativelyto the hub and at the same speed, thereby remaining stationary.

In a preferred embodiment one end of the coiled element is secured tothe fixed part of the vehicle, and the coil end housed in thenon-rotating housing is fixed to the same non-rotating housing. Thecoiled element will therefore cooperate with the gear assembly forsupporting the non-rotating housing against rotation.

In this second embodiment, the non-rotating housing and the secondhousing fixed to the vehicle are both externally toothed housingswherein the coiled element is partially lodged. For example, thenon-rotating housing is a first housing slidingly mounted on the hub,facing the driver and providing a support for a DAB module, and thesecond housing on the fixed part of the vehicle is secured to a fixedcover of the steering shaft.

Axial forces applied to the ring portion of the steering wheel, forinstance by the driver, are sustained by the steering shaft to which thesteering wheel armature is directly coupled via the hub. Axial forcesapplied on the non-rotating housing, for instance by the driveractuating the acoustic horn by pushing the DAB module, are sustained bythe first and second housings, either directly or with the interpositionof sliding elements or bearings.

By providing the aforesaid gear assembly for supporting the non-rotatingfirst housing, the steering wheel armature can be directly coupled tothe steering shaft. This feature is particularly advantageous since thesteering wheel can be easily assembled on the vehicle simply by fittingthe hub on the steering shaft and securing the second fixed housing tothe steering shaft cover, for instance by means of a clamp. Mounting ofthe steering wheel on the respective vehicle can be carried out in shorttime by a non specialized operator.

Thus, the steering wheel of the present invention allows stationarymounting of a driver airbag module and is unexpensive and easy tomanufacture and assemble. The coiled element and the housings, togetherwith the gears, can easily be pre-assembled on a steering wheel armaturethat is directly connectable to a steering wheel shaft in a traditionalway.

The gear assembly can be mounted on the hub housing by means of bearingsand levers which are biased by a spring to compensate for the mechanicalclearance between various gears. Alternatively a torsion can be appliedto the coiled element before assembling the same with the non-rotatinghousing and the fixed part of the vehicle, i.e. the coiled element ispreloaded, thereby imparting a force to the gear assembly, whenassembled, to compensate for mechanical clearances.

Moreover the steering wheel of the invention overcomes at the same timethe drawbacks of prior art steering wheels for what concerns stabilityof the non-rotating housing and the cabling of the DAB module.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference tothe drawings enclosed as a non-restrictive example, where:

FIG. 1 is an exploded view of a steering wheel according to the presentinvention;

FIG. 2 is a side view of the steering wheel shown in FIG. 1, in apartially assembled configuration;

FIG. 3A is an exploded view of a first portion of the steering wheelshown in FIG. 1;

FIG. 3B is an exploded view of a second portion of the steering wheelshown in FIG. 1;

FIG. 4 is a perspective view of a component of the steering wheel shownin FIG. 1; and

FIG. 5 is a side view of the component shown in FIG. 4;

FIG. 6 is an exploded view of a second steering wheel according to thepresent invention;

FIG. 7 is a section view of the steering wheel shown in FIG. 6;

FIG. 8 is an exploded view of a detail of the steering wheel shown inFIG. 6;

FIG. 9 is a perspective view of the detail of the steering wheel shownin FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

An exploded view of a steering wheel according to the present inventionis shown in FIG. 1. The steering wheel comprises an armature 1 that maybe of a traditional type, a hub 2, one or more spokes 22 and a rim 23.The hub 2 is coaxially fixable to a steering wheel shaft 7 (FIG. 2)along a common axis of rotation X-X. The hub is provided with a throughopening 3 that connects a side 24 of the hub 2 that will be proximalwith a vehicle driver with an opposite side 25 of the hub 2 that will bedistal from a vehicle driver, i.e. the side proximal a vehicle steeringcolumn. In the embodiment shown in FIG. 1, the opening or aperture 3 ispositioned on the hub 2 spaced radially apart from the axis of rotationX-X.

The steering wheel has a coiled element 5 comprising coils 53-56 thatare intended to pass through the through opening 3 of the hub. The coilswind, or spiral, in a continuous curve around a longitudinal axis. Theoverall shape of the coiled element is preferably cylindrical such thatthe coiled element has a helical-like structure, as the one shown in thefigures. Alternatively, the coiled element may have other shapes, forinstance having a longitudinal cross-sectional shape that is elliptical.The coiled element 5 is coaxial with the hub 2 and the steering shaft 7along the axis of rotation X-X.

As shown in FIG. 2, after assembly of the steering wheel the coiledelement 5 is at least partially placed around the steering shaft 7. Inthis first embodiment, the coiled element 5 is rigid against torsion andis intended to retain against rotation a non-rotating housing 41 mountedon hub 2. One end 51 (FIG. 5) of the coiled element 5 is fixed to thenon-rotating housing 41 arranged on the side 24 of the hub 2 that willbe proximal to a vehicle driver and a second end 52 of the coiledelement is fixed to a non-moving part of a vehicle, for instance a frameportion of the vehicle instrument panel. In the shown embodiment, thesecond end 52 of the coil is housed in and fixed to a second housing 61that is fixed to the vehicle (i.e. is stationary).

Thus, coiled element 5 is restrained against rotation around itslongitudinal axis and consequently also the non-rotating housing 41 isprevented from rotating when the steering wheel is rotated.

With reference to the FIGS. 1-2 and 4-5, when the driver rotates thesteering wheel, the coiled element 5 moves along a curved path into oraway from the hub 2, i.e. the opening 3 runs along the coils 53-56 andmore coils will be positioned either on a side 24 of the hub 2 that willbe proximal to a vehicle driver or, vice versa, on an opposite side 25of the hub 2 that will be distal from a vehicle driver, i.e. the sideproximal a vehicle steering column. When the steering wheel is rotated,the coils pass through the opening 3 in the hub 2 along a curved pathdefined by the coils. The hub 2 does not move longitudinally along theaxis of rotation X-X, i.e. it is coupled to the steering shaft 7 in sucha way that the hub rotates around the axis of rotation X-X but is notrelocated along the length of the same axis. Consequently screwing andunscrewing of the coiled element 5 through the hub 2 requires the coilsto axially move forward and back respectively. In other words, when thecoiled element 5 screws through the hub 2, the coils near the first end51 are relocated along the axis of rotation X-X toward the driver, i.e.some coils may pass through the hub opening 3 from the side 25 of thehub 2 that will be distal from a vehicle driver, i.e. the side proximala vehicle steering column to the side 24 of the hub 2 that will beproximal with a vehicle driver. On the contrary, when the coiled element5 unscrews from the hub 2, the coils near the second end 52 of thecoiled element are relocated along the axis of rotation X-X toward thesteering shaft, i.e. some coils may pass through the hub opening 3 fromthe side 24 of the hub 2 that will be proximal with a vehicle driver tothe opposite side 25 of the hub.

Axial movement of the coils 53-56 may be provided in different ways. Forinstance, the coiled element 5 may be rigid and the first end 51 andsecond end 52 are coupled to support elements that are at least in partextensible and compressible along the axis of rotation X-X but areimpeded from rotation around the same axis. Alternatively the ends 51,52 of the coiled element may be coupled in a slideable manner to axialslots provided in the non-rotating housing or in the fixed part of thevehicle. However, this arrangement would complicate the designing of thesteering wheel, and an axially deformable coiled element 5 is preferred.

Preferably the coiled element 5 is made of a material that allows theextension and compression of the coiled element along the axis ofrotation X-X, for instance a plastic material, being at the same timerigid against torsion around axis of rotation X-X. Axial movement of thecoils may be obtained by displacing some coils 53-56 and compressingother coils when the ends 51, 52 of the coiled element are firmlysecured. FIG. 5 shows the coiled element 5 wherein the pitch between thecoils 53, 56 nearest to the first end 51 and the second end 52 issubstantially constant. The pitch between the coils 54, 55 is greaterthan the one between the remaining coils, i.e. a portion A of the coiledelement 5 is axially displaced from another portion B of the coiledelement. This is achieved by stretching a length 60 of the coiledelement 5, i.e. by extending a portion of a coil along the axis ofrotation X-X, by virtue of the hub 2 being positioned between adjacentcoils 54, 55.

FIG. 2 shows the steering wheel of the invention wherein the hub 2 ispositioned between the coils 54, 55 illustrated in FIG. 5. The number ofcoils may be such that when the steering wheel is in its neutralposition, thus guiding the vehicle in a straight direction, half of thecoiled element 5 is positioned on the side 24 of the hub 2 that will beproximal with a vehicle driver and half is positioned on the oppositeside 25 of the hub facing the instrument panel or the steering column.In the embodiment shown in the figures, the coiled element 5 comprisesfive coils.

When the hub 2 rotates, coils 53-56 move through opening 3 in hub 2. Thepitch between two consecutive coils sandwiching the hub 2 increases toaccommodate hub 2. A further rotation of the hub 2 leads to arepositioning of the same hub 2 between different coils, i.e. the coilsinitially sandwiching the hub return to their initial axial extension orpitch.

In order to minimize the axial extension of the coiled element 5, thecoils nearest to the ends 51, 52 of the coiled element 5 are axiallycompressed and contained in suitable housings 41 and 61, i.e. the coilsmay be pushed to abut one the other, thus limiting axial extension.

As shown in FIGS. 2, 4 and 5, coiled element 5 is provided with a slot57 running continuously along the coils from the first end 51 to thesecond end 52 of the coiled member. As best shown in FIGS. 2 and 5, theslot 57 is arranged within the coils, i.e. the coiled member has a Ushaped cross section defining the slot 57. The slot 57 conveys wires 58or other conductors of electric current or signals to devices installedon the non-rotating housing 41. In this way the coiled element 5 is usedas a conveyor to carry conductors of electric current or signals orwiring harnesses 58 to the non-rotating housing 41 through the hub 2with no need for an expensive and complicated traditional clock-springconnection. The two housings 41, 61 have openings 75, 68 therein tofacilitate passage of the conductors 58 of electric current or signalsinto and out of the housings.

The non-rotating housing 41 can thus support devices such as LCDdisplays, radio controls and/or an airbag module. The non-rotatinghousing 41 may itself house an airbag module (which may be adapted to befixed to the end 51 of the coiled element 5).

As shown in FIGS. 1 and 3B, the non-rotating housing assembly 4comprises a non-rotating housing 41 intended to contain the coils 51, 56that will remain on the side 24 of the hub 2 that will be proximal witha vehicle driver. The non-rotating housing 41 is substantially the sameas the second housing 61 of FIGS. 1 and 3A. The exterior of housings 41,61 is best shown in FIG. 3B and the interior of the housings is bestshown in FIG. 3A. The only significant difference between the twohousings is that the non-rotating housing 41 does not need to havemounting holes 70, as used in the second housing 61 to attach the secondhousing to a fixed, non-moving part of the vehicle. Each of the housings41, 61 has a substantially cylindrical shape, an outer circumferentiallyextending wall 76, 77 and an inner sleeve 44, 64 what cooperate todefine a circumferentially extending space for receiving a portion ofthe coiled element. As the steering wheel is assembled, a portion of thecoiled element 5 is placed around the sleeves 44, eventually abutting onthe same. The sleeves 44, 64 may be made of, or covered with, a materialhaving a low friction coefficient so to allow an easy sliding of thecoils along the sleeves longitudinally with respect to the axis ofrotation X-X of the steering wheel. The non-rotating housing 41 iscoupled to the first end of the coiled element 5. On the central sleeve44, 64, which have the same function in both housings 41, 61 are locatedtwo projections 67 that are complementary with and mated to the notches59 in the coils to avoid rotation of the coiled element 5 and thus avoidrotation of the non-rotating housing 41.

The non-rotating housing 41 is sandwiched between two coupled rings 42,43. The first ring 42 is coupled to the armature 1, for instance to thehub 2 and rotates with the same. The ring 42 is provided with a ledge 46on which a corresponding flange 45 of the non-rotating housing 41 slideswhen relative rotation occurs between the non-rotating housing 41,retained by the coiled element 5 against rotation, and the ring 42jointly rotating with hub 2. The second ring 43 retains the non-rotatinghousing 41 on the ring 42. Screws or equivalent means are coupling therings 42, 43 and to the hub 2. Put another way, the two rings 42, 43cooperate to provide a raceway or track that accommodates thecircumferential flange 45 of the non-rotating housing 41, and while therings rotate with the steering wheel the flange 45 simply slides in thetrack without rotating while the rotating rings secure the non-rotatinghousing to the steering wheel. It is evident that non-rotating housing41 only slides on the rotating ring 42, i.e. on the hub 2, but itsmovements along, as well as rotations around, rotation axis X-X areinhibited.

As shown in FIGS. 1 and 4, the coils of the coiled element 5 areprovided with notches 59 intended to engage corresponding projections 67provided on the sleeves 44, 64 to impede rotation of the coiled element5.

Preferably, the non-rotating housing 41 serves as a support for a staticdriver airbag (DAB) module that does not rotate with the steering wheel.

The second end 52 of the coiled element is firmly coupled to a secondhousing 61 similar to the non-rotating housing 41. FIG. 3A shows thesecond housing 61 and mounting respective rings 62, 63. Coils 52, 53remaining on the side 25 of the hub 2 that will be distal from a vehicledriver are contained within the second housing 61.

The ring 62 is secured to the hub 2, on the side 25 of the hub 2 thatwill be distal from a vehicle driver, thus jointly rotating with thehub. The ring 62 is provided with a ledge 66 on which the correspondingflange 65 of the housing 61 slides when the ring 62 and the hub 2rotate. Another ring 63 is coupled to the ring 62 to sandwich the secondhousing 61. In this embodiment the second housing 61 and the mountingrings 62, 63 interact in the same way as described above so that themounting rings rotate with the steering wheel hub 2 but the secondhousing 61 does not rotate.

The second housing 61 is secured to a fixed part of the vehicle, forinstance a frame part of the vehicle, by way of traditional means suchas screws, nuts, bolts, etc. extending through mounting holes 70 in thesecond housing. By virtue of this coupling the coiled element 5 and thenon-rotating housing 41 are impeded from rotating.

The non-rotating housing 41 and the second housing 61 act ascompensators that exchange the coils 53 of the coiled element 5 axiallymoved by the hub 2 rotating clockwise or counterclockwise.

The steering wheel is easy to assemble as shown in FIG. 2 (wherein theouter circumferential wall 76, 77 of the housings 41, 61 are not shownto allow viewing of the relationship of the coiled element 5 to thewalls of the sleeves 44, 64). It is sufficient to pass the coiledelement 5 through the opening 3 in the steering wheel hub housing H,couple the ends 51, 52 of the coiled member 5 to the respective housings41, 61 and finally couple the housings 41, 61 to the hub 2 using themounting rings 42-43 and 62-63.

FIG. 6 is an exploded view of a second embodiment of the steering wheel;in this embodiment the same reference numbers are used for the sameparts. In the embodiment of FIGS. 6-9, the non-rotating housing 41A iscoupled to a stationary portion, i.e. second housing 61A, of the vehicleby way of a gear means. The coiled element 5 has the function ofconveying the electric wires 58 (FIG. 5) and preferably also ofsupporting against rotation the non-rotating housing 41 (as abovedisclosed) together with gear means G. In a further embodiment, coiledelement 5 is only a means of housing the electric wires. Advantageously,as in the previous embodiment, armature 1 is coaxially and directlycoupled to the steering shaft 7 in a traditional way, i.e. by means of anut 73 screwed onto the steering shaft thread 72.

The non-rotating housing 41A is externally provided at its peripherywith teeth 41B intended to match the teeth of the gear means G. Thestationary portion 61A is a second housing externally provided withteeth 61B that match and engage the teeth of gear means G. The twohousings 41A and 61A are mounted on opposite sides of casing H, that isfixed to face 25 of the armature 1 and provides a hub with an opening 3.When the steering wheel is assembled, the coiled element 5 is partiallylodged in housing 41A and partially lodged in housing 61A, as shown inthe section view in FIG. 7. Thus, the hub H, on which the steering shafthas to be fixed, provides a recess, by means of casing H, in whichnon-rotating housing 41A is located; this arrangement advantageouslyresults in a steering wheel wherein the housing 41A is substantiallyflush with the armature part 25, i.e. the space for the DAB is the sameas in embodiments having a rotating DAB.

Gear means G comprises a first gear G1 and a second gear G2 coaxiallymounted on the same driving shaft G3 at a distance. The first gear G1 ismatching the teeth 41B of housing 41A and the second gear G2 is matchingthe teeth 61B of housing 61A. The two opposite ends of the driving shaftG3 engage the hub casing H by means of bearings BE and respective levers81, 82 (FIG. 6) which, together with lever 83 and one or more biasingsprings, provide for compensation of mechanical clearance between gearsG1, G2 and the toothed housings 41A, 61A. The portion G3 of the shaft ofgear means G is housed in a hole 45 provided in hub casing H. Therefore,gear means G is rotated with the hub H and will rotate around its axisY-Y when rotated by the hub casing H.

Alternatively, if the levers 81-83 are not provided, the coiled element5 is pre-loaded, i.e. a torsion is applied to the same before itsassembling with gear means G, in order to compensate for mechanicalclearance between the gear means G and both the housings 41, 61. Inother words, the coiled element has a function of a biasing spring.

As previously mentioned, hub casing H is fixed to, or integral with thesteering wheel and moves with it. The hub casing H is shown in FIGS. 6and 7 screwed on the steering column side 25 of armature 1. One or morebearings BE are provided for promoting rotation of the gear means Garound its own axis Y. As the driver rotates the ring portion 23 of thesteering wheel, also the hub H is rotated. This causes gear means G torotate with the hub H around the axis X-X of the steering shaft, in aclockwise or counter-clockwise direction. Such a rotation causes theteeth of the first gear G1 and the second gear G2 to engage the teeth41B and 61B of the housings 41A and 61A respectively, thereby causingthe same gear means G to rotate also about its own axis Y.

The hub H is directly coupled to the steering shaft 7. The housing 41Arotates at the same speed but in the opposite direction relatively tothe hub H and steering wheel 1. In other words the gear means G and thetoothed housings 41A and 61A provide a gear ratio 1:1 for the rotationwith respect to the hub H (in the opposite direction). Thus the housing41A remains stationary with respect to the driver as the steering wheelis rotated.

FIG. 9 shows an enlarged perspective view of the housings 41A and 61Aand the gear means G in the positions they take when the steering wheelis assembled. As it can be seen, the first gear G1 and the second gearG2 simultaneously match the respective housing 41A or 61A. The drivingshaft G3 is rotated by the hub H around the steering wheel axis X-X,which is also the axis of the housings 41A, 61A. Thus the gears G1 andG2 rotate around the toothed periphery of the housings 41A, 61A, thiscausing the same gear means G to rotate about its own axis Y in theopposite direction.

As shown in FIG. 6, a DAB module is mounted onto housing 41A, forinstance by means of screws, through the hub. The coiled element 5provides the passage for the necessary wirings through the casing H andnon-rotating housing 41A up to aperture 3 of the hub housing H.

The housings 41A and 61A support axial forces applied by the driver tothe DAB module, for instance when operating the horn actuator. Thehousing 61A is fixed to the steering shaft cover 71 which is secured toa fixed portion of the vehicle and the housing 41A slides on the hub Hor other interposition elements, such as element 42A. Axial forcesapplied on the ring portion 23 are sustained by the steering shaft 7 towhich the hub is directly coupled.

As shown in FIGS. 6 and 7, housings 41A and 61A are both supported onsteering shaft 7 with bearings 84 and sliders 86 that are secured to therespective housings in a way known per se, e.g. with shown washers 85

The steering wheel of the present invention may be provided with thesliding contact 90 shown in the FIG. 6. Such contact 90 would allow foroperating an electric device mounted on a rotating part of the steeringwheel, for instance a horn actuator arranged on the ring portion 23.

The steering wheel of the present invention has various advantages overprior art steering wheels provided with stationary hub portions.

The number of components or elements is minimized. Moreover the coiledelement 5 and the associated housings 41, 61 and 41A, 61A can be made ofa plastic material. Consequently the steering wheel is much less noisyand less expensive than known solutions providing multiple satellitegears, duplication of the steering shaft, drive-by-wire, etc.

The housing 41, the gear means G and the levers 81-83 are arrangedwithin the hub H which is secured to the armature 1 by means of screws(or is integral with it). The housing 61 is secured with the housing 63to the steering shaft cover 71 (which is a stationary part of thevehicle) by means of the clamp 74. The steering wheel, so pre-assembled,is mounted on the steering shaft 7 and secured to the same by way of thenut 73.

Final assembling of the steering wheel with the vehicle involves thedirect connection of the hub 2 to the steering wheel shaft 7, with noduplication of the same shaft. Safety of the connection is thusguaranteed.

Dimensions of the coiled element 5 and its housings 41, 61 may be easilyadapted to be fitted in most common armatures, with evident advantagesin minimizing production costs and in providing customized aestheticsolutions.

The steering wheel shown in the FIGS. 6-9 has many advantages over priorart solutions. Drawbacks of the prior art solutions for what concernsthe cabling of the DAB module are overcome by providing the coiledelement 5 for conveying the electric wires. The coiled element 5provides an easy, effective and unexpensive way to convey the wires tothe DAB module. No expensive “clockspring” connectors have to be used.

Drawbacks of the prior art solutions for what concerns stability of thenon-rotating portion are overcome by providing the direct coupling ofthe hub 2 to the steering shaft 7 and a gear means G to transmitrelative rotation to the non-rotating portion 41. Advantageously, thedriving shaft G3 is not fitted for its entire length in a seat providedacross the hub 2, as in the solution disclosed in DE 3413009 A1, butengages the external hub casing H and the same hub H with its ends, thisminimizing or avoiding misalignment of the first gear with respect tothe second gear as the hub H is rotated.

Any movement of the non-rotating portion 41A is prevented as thesteering wheel is rotated. This is achieved by virtue of the rigidity ofthe gear means G and the housings 41A and 61A, for instance made ofmetal or an hard plastic as ABS, which do not undergo appreciabletorsion. Rigidity can be maximized by fixing one end of the coiledelement 5 to the housing 61 and the remaining end of the coiled element5 to the housing 41. In this case gear G and housings could be all madeof suitably rigid plastics, the sum of their single contributions beingsufficient to provide sufficient rigidity of the system.

The coiled element 5 can also be preloaded to apply a torsion force tothe housings 41A and 61A which compensate for the clearance with therespective gears G1, G2 when the steering wheel is assembled. This isobtained by initially assembling housings 41A and 61A on hub casing H inan arrangement out of alignment. When gear means is matched with teeth41B and 61B one of the housings (usually 41A) is rotated with respect tothe other, to align the housings with gear means G. This rotation willapply a torsion force to the coiled element that will thus act as aspring an compensate possible clearances. Alternatively, the gear meansG is coupled to the hub housing H by the interposition of the biasedlevers 81-83.

1. A steering wheel comprising an armature (1) having a hub (2, H) andmeans to directly couple said hub to a vehicle steering shaft (7), thehub (2, H) being provided with an opening (3), and a non-rotatinghousing (41, 41A) assembled on a side (24) of the hub (2, H) that willbe proximal with a vehicle driver, a coiled element (5) that extendsthrough said opening (3) in the hub (2, H) to carry one or more electricwires and that is fixed to at least a fixed part (61, 61A) of thevehicle, the coiled element (5) spiraling through said hub (3) when thesteering wheel is rotated, and a second non-rotating housing (61, 61A)fixed to a fixed part of the vehicle, wherein said first non-rotatinghousing (41A) and said second non-rotating housing (61A) are providedwith teeth (41B, 61B) and further comprising a gear means (G) having anaxis of rotation (Y-Y) for matching said teeth (41B, 61B) while beingrotated by said Hub (H) around an axis (X-X) of the vehicle steeringshaft (7) thereby rotating also around its own axis (Y-Y).
 2. (canceled)3. The steering wheel of claim 1, wherein said coiled element (5)housing electric wires is axially elastically extendible andcompressible along the axis of rotation (X-X) of the steering. 4.(canceled)
 5. The steering wheel according to claim 4, wherein said gearmeans (G) comprises a first gear (G1) to match said non-rotating housingand a second gear (G2) to match said fixed part (61A), said first andsecond gears being fixed coaxially on the same driving shaft (G3) whichengages said hub (H) at a distance from the axis (X-X) of the steeringshaft (7).
 6. The steering wheel according to claim 5, wherein the gearratio between said gear means (G) and both said non-rotating housing(41A) and said second (61A) is such that as the steering wheel (1) isrotated, the non-rotating housing (41A) rotates in the oppositedirection relatively to said hub (H) and at the same speed, therebyremaining stationary.
 7. The steering wheel according to claim 1,wherein an end of said coiled element (5) is secured to said fixed part(61A) of the vehicle and the opposite end is secured to saidnon-rotating housing (41A).
 8. The steering wheel according to claim 7,wherein said coiled element (5) is rigid against torsion.
 9. Thesteering wheel according to claim 1, wherein at least a portion (45) ofthe driver side non-rotating housing (41,41A) is slidable on the hub (2,H) when the steering wheel rotates.
 10. The steering wheel according toclaim 1, wherein said driver side non-rotating housing (41A) and saidsecond housing (61A) are externally provided with teeth respectivelymatching said first gear (G1) and said second gear (G2) of said gearmeans (G).
 11. The steering wheel according to claim 1, wherein at leasta portion (65) of fixed part (61, 61A) of the vehicle is slidable on thehub (2,H) when the steering wheel rotates.
 12. The steering wheelaccording to claim 1, wherein the coiled element (5) is a cylindricalhelix arranged coaxially with the steering wheel shaft (7).
 13. Thesteering wheel according to claim 1, wherein the coiled element (5) isprovided with a slot (57) to convey a conductor of power or signals (58)through the opening (3) in the hub (2).
 14. The steering wheel accordingto claim 13, wherein the coiled element (5) comprises coils (53) and theslot (57) runs along the coils (53) of the coiled element (5).